Palpatine was definitely an effective villain in terms of getting things accomplished, considering that he managed to pull off a pretty complicated plan of:

• Start a blockade of the planet Naboo in order to get the current Chancellor in a place of political suicide
• Become Chancellor
• Orchestrate a war on two fronts
• Slowly condition a teenage boy to be ripe for indoctrinating into a murder cult
• Murder all the Jedi through secret protocols in the manufactured soldiers he secretly had funded for the war he orchestrated on two fronts.
• Get an entire galaxy to give up its Republic government in exchange for a totalitarian Empire
• Keep that totalitarian Empire running for 20 years.